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GENEVA, Switzerland (CNN) -- Osman Ratib, professor and chief of nuclear medicine at the University Hospital of Geneva, has co-created a computer software program called Osirix. It enables medical professionals to view medical images on their iPods, saving them and the hospitals they work for thousands of dollars in expensive equipment.

A year and a half ago, Antoine Rosset, another radiologist and software developer, and I decided to develop software for physicians to view medical imaging on personal computers.

Radiology has moved from traditional X-rays to scanners to multi-dimensional imaging, 4D and 5D images, which is moving imagery in 3D.

Medical imaging these days is much more than just looking at slices through the body -- it's about looking at the body in motion, in function. We're dealing with images that are more than just 2D, black and white images.

The problem is equipment which can view and manipulate these images is not widely available. It's not just radiologists -- who usually have access to this sort of equipment -- who rely on images. A whole lot of medical experts use evidence based on data and we need tools for that.

Existing tools are either too expensive, too complicated or are simply not available.

We wanted to create something for non-radiologists to use, for surgeons or general physicians to view images.

We chose to create the software for Macs, as it's no secret that they are known for their graphic ability. They have huge processing power for 3D and 4D images.

CDs aren't big enough, memory sticks are not big enough, but I had my iPod, which has 40GB of memory just there. We rigged the software so that you can click to store the images on the iPod, and subsequently view them in Osirix directly from the iPod.

After we figured out that the iPods were a practical way of carrying these images, Apple brought out the photo iPod a few months later. That meant the images could also be viewed on the devices.

Instead of the usual jpeg format, medical images are stored in a format called Diacom (Digital Imaging and Communications in Medicine) so we had to create a function on the software that allowed the format to be modified so they could be visible on the iPod.

The software also incorporates Apple's instant messaging system, iChat, so that other users of the system can see what you have on your screen, which means you can show images to colleagues remotely.

IChat may not always provide the best video-quality images, depending on the network bandwidth available, but it's cheap and easy to use in comparison with the alternatives.

We can also use Apple's Dot Mac system as a shared disc for storing images, for back up. You pay $100 a year and you get 80GB of space. In the same way my mother can access photos of my children if I give her access to my personal Dot Mac system, my colleagues can access images of my patients.

There are things we have in place to ensure security and patient confidentiality. There are rules to go by. It's not the tools that pose a security risk -- it's the users. The software has a function that enables the physician to strip the image of any personal data that identifies the person, like their name, their date of birth etc. As long as that is done then it is a secure, anonymous system.

The software is open source so the code is available on the Net for people to hack and improve. In our recent surveys we estimated that we have 6,000 active users worldwide. The past two months showed an average of 200 downloads per day, with peaks up to 1,000 downloads per day when new versions were released.

It's not rocket science but it's taking something that's been designed for the consumer market and using it for something that's medically driven.